Method for relieving waterlogging disasters in cotton flowering and boll-forming periods through cooperation of shading and chemical regulation and control

Abstract

The invention discloses a method for relieving waterlogging disasters in a cotton flowering and boll-forming period through cooperation of shading and chemical regulation and control. The method comprises the steps that a sunshade net with the light transmittance of 35%-55% is erected within 12-24 hours after the cotton field is waterlogged, and the operation lasts for 5-6 days after water recession; and spraying a compound solution of sodium nitroprusside and melatonin within 2 hours after the shading is relieved. The waterlogging disaster in the cotton flowering and boll-setting period is relieved through the cooperation of shading and chemical regulation, the yield loss caused by waterlogging-high temperature cooperative stress can be reduced by 35% or above, salt-waterlogging-high temperature composite stress is relieved, and the yield loss is reduced by 40% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of cotton waterlogging-resistant cultivation, and specifically relates to a method for alleviating waterlogging disasters in the flowering and boll-forming period of cotton through coordinated shading and chemical regulation, and is particularly suitable for cotton-growing areas in the Yellow River Basin and the Yangtze River Basin. Background Art

[0002] Cotton is a major cash crop in my country, widely cultivated and used for a wide variety of purposes. The cotton industry holds a crucial position in the national economy. Therefore, ensuring the sustainable and healthy development of cotton production is of vital importance to my country's national economy. Cotton-growing areas in the Yangtze and Yellow River basins frequently experience flooding during their growing season, with the flowering and boll-forming period from July to August being particularly critical. This period is not only crucial for cotton yield development but also a peak period for climate-related disasters. When cotton plants experience waterlogging stress, root hypoxia and impaired photosynthesis can cause large numbers of buds and bolls to drop, resulting in seed cotton yield losses of up to 20%-50%. When accompanied by high temperatures (daily high temperatures ≥35°C), this combined "heat-waterlogging" stress can exacerbate the effects of waterlogging by exacerbating membrane lipid peroxidation (malondialdehyde levels can increase by 80%-120%). With global warming, the frequency and severity of combined stress in the cotton-growing areas of the Yangtze and Yellow River basins are increasing.

[0003] The current flood control technology system primarily focuses on drainage and waterlogging reduction, including mechanical drainage, ditch clearing, and soil surface management. While highly effective, these measures often require substantial investment, depending on the level of water conservancy development. Notably, the current system fails to fully account for the synergistic effects of high temperatures and waterlogging, severely limiting the effectiveness of single drainage measures. Simultaneously draining waterlogging while avoiding high temperatures, thereby mitigating the synergistic effects of these two factors, should be a key approach to addressing waterlogging during the flowering and boll-forming period.

[0004] It is generally believed that shading affects plant growth and development, especially long-term shading, which causes leaves to grow larger and thinner to adapt to insufficient light. Boll number is particularly sensitive to shading. Long-term shading during the flowering and boll-forming period can increase bud and boll shedding and reduce boll set (Guo Xingxian et al., 1959). Shading can reduce boll number per plant by 52% (Zhou Zhiguo et al., 2002; Eton et al., 1954). Insufficient light also affects cotton fiber quality, with specific strength and micronaire values significantly decreasing after shading (Zhou Guisheng et al., 2003).

[0005] Existing research has largely focused on the negative effects of shading, while ignoring its potential value in stress resilience. In particular, there are no reports of research using shading to mitigate the stress effects of waterlogging during the flowering and boll-forming period, either domestically or internationally. Summary of the Invention

[0006] To address these issues, the present invention provides a method for alleviating waterlogging during the flowering and boll-forming period of cotton by synergistically shading and chemical manipulation. Within 12-24 hours after waterlogging, a shade net with a light transmittance of 35%-55% is installed in the cotton field, maintaining the net until 5-6 days after the water recedes. Within 2 hours of removing the shade, a mixed solution of sodium nitroprusside and melatonin is sprayed. This method significantly reduces the damage caused by combined waterlogging and high temperature stress to cotton.

[0007] The technical solution of the present invention is: a method for alleviating waterlogging disasters during the flowering and boll period of cotton by synergistically combining shading and chemical regulation, which is characterized by:

[0008] (1) Set up shade nets within 12-24 hours after cotton fields are flooded, with a light transmittance of 35%-55% (corresponding to a shading rate of 65%-45%), and continue shading for 5-6 days after the water recedes;

[0009] (2) Spray the leaves with a compound solution within 2 hours after the shading is lifted, wherein the compound solution contains a final concentration of sodium nitroprusside of 80-100 μM, a final concentration of melatonin of 100-120 μM, and an adjuvant.

[0010] Furthermore, the auxiliary agents are: final concentration 0.05-0.2% Tween-20 and final concentration 0.03-0.08% sodium carboxymethyl cellulose (preferably final concentration 0.1% Tween-20 and final concentration 0.05% sodium carboxymethyl cellulose); the solvent used in the above solution is phosphate buffer with pH 6.0-6.5.

[0011] Furthermore, black high-density shade nets were used for shading, with a mesh density of 120 meshes (aperture 0.125 mm), 40-50 cm away from the top of the cotton plant canopy; after the shading ended on the 5th-6th day, the nets were gradually removed from 17:00 to 20:00 on the same day to avoid strong light stress.

[0012] Furthermore, the light transmittance of the saline-alkali cotton field is 40%±5%, and the sunshade net is 40 cm away from the canopy; the light transmittance of the conventional cotton field is 50%±5%, and the sunshade net is 50 cm away from the canopy.

[0013] Furthermore, in the compound solution, the molar concentration ratio of sodium nitroprusside to melatonin is 1:1.2-1.5, wherein the molar concentration ratio in saline-alkali cotton fields is 1:1.5.

[0014] Furthermore, the spraying was carried out using drone atomization at a rate of 400L / ha.

[0015] In the present invention, shading reduces the canopy temperature by 4-6°C, reduces the transpiration rate by 30% to 40%, and alleviates the imbalance between root water absorption and transpiration; the carbon monoxide and nitrogen donor sodium nitroprusside releases nitric oxide, which activates superoxide dismutase and catalase to eliminate reactive oxygen; melatonin upregulates the expression of auxin and cytokinin synthesis genes GhYUCCA5 and GhIPT3, promotes new root formation, and downregulates the abscisic acid synthesis key enzyme gene GhNCED1 to reduce abscisic acid content and reduce stomatal closure; the melatonin in the saline-alkali land adaptation scheme specifically activates the expression of the GhSOS1 gene to promote Na + Efflux, reducing Na in roots and leaves + The content is reduced, alleviating the combined stress of salt and waterlogging.

[0016] The technical effect of this invention is that shading and chemical regulation synergistically alleviate waterlogging during the flowering and boll-forming period of cotton, reducing yield losses caused by waterlogging and high temperature combined stress by over 35%. For waterlogging in saline-alkali cotton fields, shading alleviates high temperature stress by lowering canopy temperature, while the compound solution reduces waterlogging damage by promoting root repair and boll development. Together, the two alleviate the combined stress of salt, waterlogging, and high temperature, reducing yield losses by over 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the effect on the expression levels of cotton flooding response genes (GhDOF1.2, GhGhNCED, GhRBOHC, GhADH). DETAILED DESCRIPTION

[0018] The effects are described below with reference to the embodiments and drawings.

[0019] Example 1: Conventional cotton field simulated for 10 days of waterlogging (Linqing Experimental Station)

[0020] This experiment was conducted in 2024 at the Cotton Experimental Station of Shandong Academy of Agricultural Sciences (Linqing, 115°42'E, 36°61'N). The test variety was Lumianyan No. 28. The plot area was 21m 2 The row spacing was set at 1m for large rows and 0.5m for small rows, with a planting density of 4,000 plants per mu. Cotton was sown on April 25, seedlings were transplanted on May 10, and soiling was completed on June 23.

[0021] On June 30, simulated waterlogging stress treatment was initiated, with flooding lasting 10 days (water depth 15 cm). On the same day, a black high-density sunshade net (mesh density 120 mesh, light transmittance 50%, 50 cm from the canopy) was set up. After the water receded (July 9), shading was continued for 5 days until 17:30 on July 13, when the net was gradually removed. Immediately thereafter, a composite solution (sodium nitroprusside 80 μM, melatonin 100 μM, 0.1% Tween-20 and 0.05% sodium carboxymethyl cellulose) was sprayed by drone at a rate of 400 L / ha. The solvent was phosphate buffer solution at pH 6.0-6.5. A blank control ( Figure 1 The control group included waterlogging treatment, shading treatment, and waterlogging + shading. Other agronomic measures were implemented according to conventional management.

[0022] The test measured the canopy daily maximum temperature, photosynthetic rate, malondialdehyde, biological yield, boll density, boll weight and seed cotton yield, and the results are shown in Table 1. The effects on the expression of cotton genes (GhDOF1.2, GhGhNCED, GhRBOHC, GhADH) were tested, and the results are shown in Table 1. Figure 1 shown.

[0023] Table 1 Effects of shading and spraying compound solution on maximum canopy temperature, cotton yield and photosynthetic rate of waterlogged cotton

[0024]

[0025] Note: The maximum daily temperature of the canopy is the average value during the shading treatment period (15 days); the photosynthetic rate and malondialdehyde content are the measured values of the functional leaves of the main stem after 15 days of shading.

[0026] The results showed that the synergistic treatment of shading and compound solution significantly alleviated the physiological damage and yield loss of cotton caused by waterlogging and high temperature combined stress. The specific analysis is as follows:

[0027] (1) Shading significantly reduced the average daily maximum temperature of the cotton canopy (Table 1). The average daily maximum temperature of the blank control group was 35.2°C, which decreased to 30.5°C after shading, a decrease of 4.7°C. Under waterlogging, the canopy temperature of the combined shading and spraying solution treatment (30.4°C) was 4.7°C lower than that of the single waterlogging treatment (35.1°C), indicating that shading effectively inhibited high temperature stress.

[0028] (2) Shading and spraying the compound solution on flooded cotton significantly reduced cotton yield losses (Table 1). Yield data showed that the seed cotton yield of the blank control group was 4681 kg / ha, and the single waterlogging treatment resulted in a yield decrease of 46.4% (2511 kg / ha). Shading under waterlogging stress (shading-waterlogging combined stress) reduced the yield by 35.5% (3027 kg / ha), reducing the waterlogging yield loss by 23.5%; by synergistically shading and spraying the compound solution, the seed cotton yield loss of flooded cotton was reduced to 26.3% (3452 kg / ha), which was 20 percentage points higher than that of the single waterlogging treatment, reducing the seed cotton yield loss by as much as 43.3%. In addition, the boll weight of the synergistic treatment group increased significantly by 7.6% (5.12 g → 5.51 g), and the biological yield (8791 kg / ha) increased by 26.6% compared with the single waterlogging group (6946 kg / ha), and the boll density (62.7 m -2 ) Waterlogged group (50.8m -2 ) increased by 23.4%.

[0029] (3) Shading and spraying the compound solution on flooded cotton significantly reduced membrane lipid damage and adverse effects on photosynthesis. In terms of photosynthetic rate, the blank control group was 36.5 μmol CO2m -2 s -1 , the waterlogging treatment decreased to 28.6 μmol CO2m -2 s -1 (21.6% decrease), and the flooded cotton recovered to 30.5 μmol CO2m after shading. -2 s -1 The photosynthetic rate of flooded cotton was further restored to 32.6 μmol CO2m by shading and spraying the compound solution. -2 s -1 (A decrease of 10.7%). Changes in malondialdehyde (MDA) content further revealed that the degree of oxidative damage was significantly reduced through the combined treatment of shading and spraying with the solution: the blank control group had a MDA content of 43.2 nmol / g, and the MDA content under waterlogging treatment surged to 81.4 nmol / g (an increase of 88.4%). The MDA content of flooded cotton after shading was 60.3 nmol / g (an increase of 39.6%), while the MDA content of flooded cotton combined with shading and spraying with the compound solution was only 55.9 nmol / g (an increase of 29.4%). This shows that shading and spraying with the compound solution significantly reduced membrane lipid peroxidation by scavenging reactive oxygen species, enhanced photosynthesis, and laid a physiological foundation for reducing yield losses.

[0030] (4) Gene expression analysis Figure 1) showed that shading and spraying flooded cotton with the compound solution significantly reduced the expression of stress-responsive genes. Compared with the non-flooded control, the expression of the reactive oxygen species synthesis gene GhRBOHC increased by 288% under waterlogging, but this increase decreased to 149.8% under shading and further decreased to 113.1% under the combined treatment of shading and spraying. The expression of the abscisic acid synthesis gene GhNCED increased by 8.64-fold under waterlogging, but this increase decreased to 1.5-fold and 1.02-fold, respectively, under shading and combined shading and spraying. The transcription factor gene GhDOF increased by 3.63-fold under waterlogging, but this increase decreased to 2.4-fold and 1.54-fold, respectively, under shading and combined shading and spraying. Similarly, the expression of the alcohol dehydrogenase gene GhADH increased by 1.81-fold under waterlogging, but this increase decreased to 69.0% and 52.3% under shading and combined shading and spraying, respectively. It can be seen that shading can reduce the expression of stress response genes in flooded cotton, and spraying the compound solution can further reduce the expression of response genes and alleviate stress damage.

[0031] In summary, this example significantly reduced the damage to cotton from combined waterlogging and high-temperature stress by synergizing shading (50% transmittance, lasting for 5 days after water withdrawal) with a combined solution (80 μM sodium nitroprusside + 100 μM melatonin). Compared with waterlogging alone, the synergistic combination of shading and sodium nitroprusside + melatonin reduced high-temperature stress, activated stress-related gene expression, mitigated membrane damage (the increase in MDA accumulation decreased from 88.4% to 29.4%), maintained photosynthetic production (the decrease in photosynthetic rate decreased from 21.6% to 10.7%), and reduced seed cotton yield losses by 43.3%. This technology provides a reliable scientific basis for preventing and controlling waterlogging during the flowering and boll-forming period in cotton regions of the Yellow River Basin and has significant practical value.

[0032] Example 2: Cotton fields in saline-alkali land in Wudi County (actual waterlogging)

[0033] On July 10, 2024, Xixiaowang Town in Wudi County was hit by a 40mm rainfall. This caused a demonstration field of saline-alkali cotton (Lumian 522) (soil salinity 0.25% at 0-20cm depth) to remain waterlogged for eight days after the rain (water depth 10-30cm). The water gradually receded after eight days, and soil moisture returned to normal after 15 days. A high-density black shade net (45% transmittance, 40cm from the canopy) was installed the day after the flooding (July 11). After the water receded (July 18), shade was maintained for five days until July 23, and the net was gradually removed at 5:00 PM on July 24. Within 2 hours of shading being lifted, drones were used to spray a combined solution (100 μM sodium nitroprusside, 120 μM melatonin, 0.1% Tween-20, and 0.05% sodium carboxymethylcellulose) at a rate of 400 L / ha in phosphate buffer (pH 6.0-6.5). Waterlogging treatment and waterlogging combined with shading served as controls. Other field management measures followed the conventional protocol for local saline-alkali cotton fields.

[0034] The test measured the maximum daily temperature of the canopy, root dry weight, dry weight per plant, biological yield, boll density, boll weight and seed cotton yield. The test results are shown in Table 2.

[0035] Table 2 Effects of shading and spraying with compound solution on maximum canopy temperature, yield and yield components of waterlogged cotton

[0036]

[0037] Note: The maximum daily temperature of the canopy is the average value during the shading treatment period (15 days); the root dry weight and single plant dry weight are the measured values of the main stem functional leaves after 15 days of shading.

[0038] The experimental results (Table 2) show that shading combined with the combined solution significantly alleviated the negative effects of waterlogging in saline-alkali cotton fields. The average daily maximum canopy temperature of the flooded cotton (control group) was 34.1°C. This dropped to 30.2°C and 30.1°C after shading and the combined solution treatment, respectively, a decrease of 3.9°C and 4.0°C.

[0039] In terms of seed cotton yield, waterlogged cotton yielded only 2,421 kg / ha. Shading waterlogged cotton yielded 3,156 kg / ha, a 30.4% increase. Shading and synergistic spraying of the combined solution increased yield to 3,537 kg / ha, a 46.1% increase. Boll weight in the synergistic treatment increased by 17.6% (4.65 g to 5.47 g). Biomass yield (8,968 kg / ha) was 22.8% higher than in the waterlogged treatment (7,302 kg / ha), and boll density (64.7 m²) was 24.2% higher than in the waterlogged treatment (52.1 m²).

[0040] Root and plant dry weight data further validated the effectiveness of the synergistic approach. Root dry weight in the waterlogged treatment was 12.6g, while in the synergistic treatment it was 17.1g, a 35.7% increase. Plant dry weight showed a similar trend, with the waterlogged treatment reaching 71.2g and the synergistic treatment reaching 85.3g, a 19.8% increase.

[0041] In summary, this example significantly reduced the damage caused by waterlogging in saline-alkali cotton fields by synergizing shading (45% transmittance, lasting for 5 days after water withdrawal) with a combined solution (100 μM sodium nitroprusside + 120 μM melatonin). Compared with waterlogging, the synergistic approach increased seed cotton yield by 46.1%, boll weight by 17.6%, boll density by 24.2%, root dry weight by 35.7%, and biomass yield by 22.8%. This demonstrates that shading alleviates heat stress by lowering canopy temperature, while the combined solution mitigates waterlogging damage by promoting root repair and boll development. The two synergistic approaches provide an effective solution for preventing and controlling waterlogging in saline-alkali cotton fields.

Claims

1. A method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically combining shading and chemical regulation, characterized in that: (1) Set up shade nets within 12-24 hours after cotton fields are flooded, with a light transmittance of 35%-55%, and continue shading for 5-6 days after the water recedes; (2) Spray the leaves with a compound solution within 2 hours after the shading is lifted, wherein the compound solution contains a final concentration of sodium nitroprusside of 80-100 μM, a final concentration of melatonin of 100-120 μM, and an adjuvant.

2. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 1, characterized in that: The auxiliary agents are: Tween-20 with a final concentration of 0.05-0.2% and sodium carboxymethyl cellulose with a final concentration of 0.03-0.08%; the solvent used in the composite solution is a phosphate buffer with a pH of 6.0-6.

5.

3. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 2, characterized in that: The auxiliary agents include: Tween-20 with a final concentration of 0.1% and sodium carboxymethyl cellulose with a final concentration of 0.05%.

4. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 1, wherein: The shading adopts a black high-density sunshade net with a mesh density of 120 meshes, which is 40-50 cm away from the top of the cotton plant canopy.

5. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 4, characterized in that: The light transmittance of the saline-alkali cotton field is 40%±5%, and the sunshade net is 40 cm away from the canopy.

6. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 4, wherein: The light transmittance of the non-saline-alkali cotton field is 50%±5%, and the sunshade net is 50 cm away from the canopy.

7. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 1, wherein: After the shading is completed on the 5th to 6th day, the nets are gradually removed between 17:00 and 20:00 on the same day to avoid strong light stress.

8. The method for alleviating waterlogging disasters during the flowering and boll stage of cotton by synergistically shading and chemical regulation according to any one of claims 1 to 7, wherein: In the composite solution, the molar concentration ratio of sodium nitroprusside to melatonin is 1:1.2-1.

5.

9. The method for alleviating waterlogging disasters during the flowering and boll-forming period of cotton by synergistically shading and chemical regulation as claimed in claim 8, wherein: For saline-alkali cotton fields, the molar concentration ratio of sodium nitroprusside to melatonin in the compound solution is 1:1.5.

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